Epidemiology of AKI: Utilizing Large Databases to Determine the Burden of AKI  Simon Sawhney, Simon D. Fraser  Advances in Chronic Kidney Disease  Volume 24, Issue 4, Pages 194-204 (July 2017) DOI: 10.1053/j.ackd.2017.05.001 Copyright © 2017 The Authors Terms and Conditions

Figure 1 Methodologic challenges in AKI epidemiology. (A) Approaches to studying AKI using observational data and their advantages and disadvantages. (B) Bias that may arise because of convenience sampling of those admitted to hospital. In this scenario, of 1000 people in the population, 250 people had AKI (25% population incidence) including 93 who died (37% fatality). If only people above the threshold are observable, 113 people have observed AKI (11% estimated population incidence) including 80 observed deaths (71% fatality). If the admission threshold changes (eg, with a new policy), this would affect both the incidence and fatality of hospital AKI. Abbreviations: AKI, acute kidney injury; ICD, International Classification of Diseases. Advances in Chronic Kidney Disease 2017 24, 194-204DOI: (10.1053/j.ackd.2017.05.001) Copyright © 2017 The Authors Terms and Conditions

Figure 2 Study of the incidence of AKI in the Grampian population 2001-2014. (A) Growth of Grampian population (red solid) and increase in the proportion of people receiving a blood test (blue dash). (B) Association between testing intensity and the incidence of new AKI presentations by day of the week 2001-2014. (C) Rates of KDIGO-AKI using creatinine change criteria (red solid and pink dot) and ICD-10 code-classified AKI (blue dash). (D) AKI incidence represented as a proportion of the tested population at risk. Abbreviations: AKI, acute kidney injury; ICD-10, International Classification of Diseases, Tenth Revision; KDIGO-AKI, Kidney Disease: Improving Global Outcomes. Advances in Chronic Kidney Disease 2017 24, 194-204DOI: (10.1053/j.ackd.2017.05.001) Copyright © 2017 The Authors Terms and Conditions

Figure 3 Mortality rates and age- and sex-adjusted rate ratios by (A-D) baseline eGFR group and acute kidney injury (AKI; 1-3 denote severity stage). Abbreviations: AKI, acute kidney injury; ref, reference group; eGFR, estimated glomerular filtration rate. Note the log scale: each increment on the y axis represents a doubling of mortality rates. Modified from Sawhney et al.,7 http://dx.doi.org/10.1053/j.ajkd.2016.05.018 under the terms of the Creative Commons Attribution License (CC BY). Advances in Chronic Kidney Disease 2017 24, 194-204DOI: (10.1053/j.ackd.2017.05.001) Copyright © 2017 The Authors Terms and Conditions

Figure 4 Percentage of people undergoing surgery who developed postoperative AKI stages 1, 2, and 3: (A) following a gentamicin policy change among people undergoing orthopedic surgery (excluding NOF). (B) People undergoing surgery of an NOF fracture (for whom the policy change did not involve gentamicin). Abbreviations: AKI, acute kidney injury; NOF, non-neck of femur. Reproduced from Bell et al.,70 http://dx.doi.org/10.1681/ASN.2014010035, with permission from the authors and publisher. Advances in Chronic Kidney Disease 2017 24, 194-204DOI: (10.1053/j.ackd.2017.05.001) Copyright © 2017 The Authors Terms and Conditions